Machines and mechanical systems with moving parts, such as motors, engines, bearings, compressors, or pumps, may generate vibrations. The vibrations may form a recognizable pattern. For example, a pattern may be characterized by a spectral distribution of the vibrations. Vibrations that are generated by mechanical systems typically have components with frequencies in the audible and ultrasonic ranges.
In many cases, a pattern of the vibrations that are generated by the mechanical system is related to a state of operation of the machine. For example, a speed of motion of a moving or rotating part may affect the vibration pattern. Thus, vibrations of a machine may be sensed and analyzed to indicate a state of operation of the machine.